1. Field of the Invention
The invention relates generally to aquarium filtration and, more particularly, to a combination physical and aerobic filter.
2. Description of the Prior Art
To combat the problem of toxic waste build-up, three types of filtration approaches are generally utilized. One approach is physical filtration wherein the suspended waste material is physically trapped by mechanical filters. The filters utilize filtration material in the form of fluffy masses of synthetic resin fibers. Sand or gravel beds are also utilized for physical filtration in undergravel type of filters.
The second well known type of filtration is chemical filtration which relates to the removal of or deactivation of mostly organics. Activated carbon and ion exchange resins are commonly used materials for chemical filtration. While the above forms of filtration are well known and frequently utilized, they are generally insufficient for purifying the water and eliminating some of the common known toxic waste products of the aquatic animals themselves.
The third type of filtration which is probably the most important and yet often least utilized, is that of biological filtration. Such biological filtration is accomplished by means of living organisms, primarily bacteria. In an aquarium the aerobic filtration is important since it serves to rid the tank of toxic ammonia.
The aerobic nitrifying bacteria have two basic requirements to carry out their functions. The first is a need for adequate oxygen. The second is that they require a place to attach themselves.
Prior art filters which provided enhanced aerobic filtration were complex, large and expensive devices. These filters referred to as wet/dry filters include a chamber providing mechanical filtration, being the wet part, and an aerobic chamber being the dry part because of the large amounts of oxygen within the aerobic chamber. One such filter is U.S. Pat. No. 3,774,766 dated Nov. 27, 1973 disclosing a filter which uses siphon tubes to remove water from the tank and a pump to return filtered water back inside the tank. This device is adapted to be placed on the outside of the aquarium tank. This filter requires a siphon to draw aquarium water into the primary filter and a pump to pump the aerobically filtered water back into the aquarium. As a result, the filter requires a balance between the input to the filter and the output of the filter to avoid either overflowing the aerobic chamber or not having sufficient water for the pump returning the water to the aquarium to operate efficiently. It also requires collection of the water dripping through the aerobic chamber to prove an adequate amount to support the return pumping of the water to the aquarium. The filter is not adaptable to use with a gravity return mechanism but uses a pump to return the water. The unit further does not have any safeguard in case the pump should clog and water overfill the chambers.
U.S. Pat. No. 5,176,824 dated Jan. 5, 1993, and assigned to the present assignee discloses an improved wet/dry filter which uses a gravity return through a slit in the bottom of the chamber and a single impeller pump to pump the water into the filter. The aerobic filter must be positioned within or above the aquarium tank. The filter must rest at a height above the water level and yet must be high enough to allow the water to trickle down through aerobic medium for proper filtering.
While previous filters have provided primary and aerobic filtration, still further enhancement and improvement are useful. It would be desirable if such a filter would be positioned completely outside the aquarium tank so that it can be easily cleaned and need not be positioned above the water level in the tank. It should also be able to have a large area for aerobic filtration, a single pump means for the flow of water into the tube and a gravity return into the aquarium tank. These and other advantages are accomplished by the present invention as will be further described in the following description.